Intercellular Communication in Retinal Development

描述（由申请人提供）：脊椎动物视网膜内的突触连接在结构上和功能上都是高度组织的。我们的主要目标是阐明视网膜回路在发育过程中组装的精确性的机制。视网膜神经节细胞（RGC）将信息从眼睛传递到大脑中的视觉目标，接收来自两种主要类别的视网膜中间神经元（无长突细胞和双极细胞）的连接。这些视网膜中间神经元共同帮助塑造RGC对光刺激的响应特性。使用谷氨酸作为神经递质的双极细胞形成光感受器和RGC之间的重要联系。双极细胞和RGC之间的突触连接在成熟时被精确地组织起来。该提案的具体目标是确定双极细胞在发育过程中如何与RGC连接，并确定视觉之前视网膜中的活动如何帮助塑造这些细胞类型之间的连接。在目标1中，通过在RGCs中表达荧光标记的PSD 95（PSD 95-FP），一种定位于突触能突触的突触后蛋白，将在整个发育过程中绘制到RGCs上的双极输入的分布和密度。实时成像方法将被用来测试的假设，即双极连接模式建立的突触形成和消除的过程中，和他们的连接模式组织的RGC树突状乔木的结构重塑的一部分。在目标2中，将通过检查在具有异常外部视网膜发育的突变动物中RGC树突结构、连接性和活性如何受到影响来确定光非依赖性光感受器传输在双极-RGC连接性成熟中的重要性。总之，这些研究将增加我们对RGC树突上如何建立突触输入以及视觉之前外部视网膜功能的扰动如何改变内部视网膜结构和功能的理解。

DESCRIPTION (provided by applicant): Synaptic connections within the vertebrate retina are highly organized both structurally and functionally. Our broad goal is to elucidate the mechanisms underlying the precision by which retinal circuits are assembled during development. Retinal ganglion cells (RGCs) that relay information from the eye to visual targets in the brain receive connections from two major classes of retinal interneurons, the amacrine cells and bipolar cells. Together, these retinal interneurons help shape the response properties of RGCs to light stimuli. Bipolar cells, which use glutamate as a neurotransmitter, form the essential link between photoreceptors and RGCs. Synaptic connections between bipolar cells and RGCs are precisely organized at maturity. The specific goal in this proposal is to determine how bipolar cells connect with RGCs during development, and ascertain how activity in the retina before vision helps shape the connectivity between these cell types. In Aim 1, the distribution and densities of bipolar inputs onto RGCs will be mapped across development, by expressing in RGCs fluorescently-tagged PSD95 (PSD95-FP), a postsynaptic protein localized to glutamatergic synapses. Live imaging approaches will be used to test the hypothesis that bipolar connectivity patterns are established by a process of synapse formation and elimination, and that their connectivity patterns are organized in part by structural remodeling of the RGC dendritic arbor. In Aim 2, the importance of light-independent photoreceptor transmission in the maturation of bipolar-RGC connectivity will be determined by examining how RGC dendritic structure, connectivity and activity are affected in mutant animals with abnormal outer retinal development. Together, these studies will increase our understanding of how synaptic inputs are established on RGC dendrites and how perturbation of outer retinal function prior to vision might alter inner retinal structure and function.